:xr-overlay {
    /* force a transparent background */
    background: rgba(0,0,0,0) !important;

    /* act as containing block for descendants */
    contain: paint !important;

    /* the following styling is identical to :fullscreen */
    position: fixed !important;
    top: 0 !important;
    right: 0 !important;
    bottom: 0 !important;
    left: 0 !important;
    margin: 0 !important;
    box-sizing: border-box !important;
    min-width: 0 !important;
    max-width: none !important;
    min-height: 0 !important;
    max-height: none !important;
    width: 100% !important;
    height: 100% !important;
    transform: none !important;

    /* intentionally not !important */
    object-fit: contain;
}
